The main entrance is via a metro station entrance located northeast of Bethesda office east. Uncharacteristically, this station doesn't have an obelisk marking its location.
Inside the station, the mezzanine and platform are relatively intact. The subway tunnels are partially destroyed, with access being limited to the tunnel openings, and the subway tracks run north to south. Located off one of the destroyed subway tunnels is a service tunnel which leads to a sewer grating ladder. This sewer grating is located south of Bethesda offices west. This station is irradiated by barrels of radioactive waste, with the largest concentrations being located on the platform, the pile of barrels near the service tunnel, and near the sewer grating ladder.
The underworks is populated by feral ghouls, and it is not uncommon to see a glowing one or a feral ghoul reaver (if Broken Steel is installed) here amongst the other types of ghouls. Upon entering, the Lone Wanderer may be swarmed by all of the nearby ghouls at once, forcing them into a fight with around 6 ghouls of varying difficulty.
- Tales of a Junktown Jerky Vendor - on a large metal pot sitting on a bench found right after coming from the tunnel at the entrance. (A)
- Grognak the Barbarian - in a storage room at the bottom of the Underworks. On a shelf next to several grenades. Note: the book blends in with the shelves, making it difficult to spot. (B)
- Mini nuke - in the storage room under a wooden crate (you need to move it manually).
- Stealth Boy - in the storage room, held in the skeleton's hand.
- Nuka-Cola Quantum - in the storage room, on the shelf.
- Entering the underworks for the first time while sneaking (or wearing the ghoul mask) causes all feral ghouls (except the glowing one) to run out of the station and engage the raiders.
- If the ghouls make it out of the underworks, they will re-spawn along with the raiders, leading to a battle every 3 game days.
Bethesda underworks appears only in Fallout 3.
Playstation 3 Xbox 360 After all add-ons are installed, the ghouls in the area may completely vanish, except for one glowing one by the stairway. [verified]